Treatment of diffuse large-cell lymphoma with anti-CD20 antibody

ABSTRACT

The present invention concerns methods for the treatment of diffuse large cell lymphoma by administration of an anti-CD20 antibody and chemotherapy. Particular embodiments include the administration of anti-CD20 antibody in combination with chemotherapy comprising CHOP (cyclophosphamide, hydroxydaunorubicin/doxorubicin, vincristine, and prednisone/prednisolone) and/or in combination with a transplantation regimen.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser.No. 09/628,187 filed Jul. 28, 2000 now U.S. Pat. No. 8,857,244, whichclaims priority under 35 U.S.C. Section 119(e) and the benefit of U.S.Provisional Application Ser. No. 60/148,286 filed Aug. 11, 1999, theentire disclosures of which are incorporated herein by reference intheir entireties.

FIELD OF THE INVENTION

The present invention concerns methods of treating intermediate- andhigh-grade non-Hodgkin's lymphomas, and lymphomas associated with a highlevel of bone marrow involvement with anti-CD20 monoclonal antibodiesand fragments thereof.

BACKGROUND OF THE INVENTION

Non-Hodgkin's lymphoma is characterized by the malignant growth of Blymphocytes. According to the American Cancer Society, an estimated54,000 new cases will be diagnosed, 65% of which will be classified asintermediate- or high-grade lymphoma. Patients diagnosed withintermediate-grade lymphoma have an average survival rate of 2-5 years,and patients diagnosed with high-grade lymphoma survive an average of 6months to 2 years after diagnosis.

Intermediate- and high-grade lymphomas are much more aggressive at thetime of diagnosis than are low-grade lymphomas, where patients maysurvive an average of 5-7 years with conventional therapies.Intermediate-and high-grade lymphomas are often characterized by largeextranodal bulky tumors and a large number of circulating cancer cells,which often infiltrate the bone marrow of the patient.

Conventional therapies have included chemotherapy and radiation,possibly accompanied by either autologous or allogeneic bone marrow orstem cell transplantation if a suitable doner is available, and if thebone marrow contains too many tumor cells upon harvesting. Whilepatients often respond to conventional therapies, they usually relapsewithin several months.

A relatively new approach to treating non-Hodgkin's lymphoma has been totreat patients with a monoclonal antibody directed to a protein on thesurface of cancerous B cells. The antibody may be conjugated to a toxinor radiolabel thereby affecting cell death after binding. Alternatively,an antibody may be engineered with human constant regions such thathuman antibody effector mechanisms are generated upon antibody bindingwhich result in apoptosis or death of the cell.

One antibody currently being investigated for the treatment ofintermediate- and high-grade lymphomas is ONCOLYM®(¹³¹I-Lym-1)(Techniclone Corp.), which is a murine IgG2a monoclonalantibody which recognizes the HLA-Drl 0 protein which is present on thesurface of over 80% of lymphoma cells. Only 2% of normal B cells(noncancerous) express the HLA-Drl 0 molecule. ONCOLYM® IgG2a monoclonalantibody is conjugated to a Iodine-[131] ⁽¹³¹I), a radioactive isotopeof iodine which emits beta irradiation for a distance of severalmillimeters, and is thereby thought to be an effective approach totargeting the outer rim of tumors and halting the progression of bulkydisease

However, a potential disadvantage in using ONCOLYM® IgG2a monoclonalantibody in advanced forms of non-Hodgkin's lymphoma is that suchlymphomas are often characterized by bone marrow involvement. Thus,administration of a radiolabeled antibody to such patients often resultsin unwanted myelosuppression and damage to healthy progenitor cells.

It would be advantageous if alternative therapies and other monoclonalantibodies could be administered to patients with intermediate- andhigh-grade lymphomas which circumvent some of the deficienciesassociated with current treatments and decrease the frequency ofrelapse.

SUMMARY OF THE INVENTION

The present invention concerns the use of anti-CD20 antibodies for thetreatment of intermediate- and high-grade lymphomas, particularly thosewhich are characterized by bone marrow involvement and bulky disease. Inparticular, the present inventors have surprisingly found thatrituximab, a chimeric anti-CD20 antibody already approved for thetreatment of low-grade follicular non-Hodgkin's lymphoma, may beeffective to treat more aggressive lymphomas as well.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to methods for treating or alleviating thesymptoms of intermediate- or high-grade non-Hodgkin's lymphoma, or otherlymphomas associated with a high degree of bone marrow involvement,comprising administering to a patient a therapeutically effective amountof an anti-CD20 antibody or other lymphoma cell depleting antibody, e.g.anti-CD19 and anti-CD22 antibodies, or a therapeutically effectivefragment thereof. The present invention also includes administeringanti-CD20 antibodies, or other lymphoma cell depleting antibodies, aspart of a transplant regimen (autologous bone marrow transplant orallogeneic bone marrow transplant or peripheral blood stem celltransplant) to improve the survival of transplant recipients.

Therapeutically effective antibody “fragments” refers to any portion ofor derivative of an antibody that is capable of delivering substantiallythe same therapeutic effect as the whole antibody when administered to apatient having intermediate- or high- grade non-Hodgkin's lymphoma(NHL), or when used as part of a transplant regimen.

As the understanding of lymphoma improves and new histopathologicvariations are diagnosed, new classification systems for the differenttypes of lymphoma have emerged. In general, for the purposes of themethods described herein, intermediate- and high-grade lymphomas aredefined as those designated in the “Working Formulation” established in1982. This system includes as intermediate-grade lymphomas follicularlarge cell (FL), diffuse small cleaved cell (DSC), diffuse mixed smalland large cell (DM), and diffuse large cell, cleaved or noncleaved (DL).As high-grade lymphomas, the system recognizes immunoblastic large cell(IBL), lymphoblastic, convoluted or nonconvoluted (LL), and smallnoncleaved cell, Burkitt's or non-Burkitt's (SNC).

Several classification systems have emerged since the proposed WorkingFormulation. For instance, a recent-classification system proposed byEuropean and American pathologists is called the Revised EuropeanAmerican Lymphoma (REAL) Classification . Although this classificationsystem does not use the terms “intermediate-” and “high-grade” NHL, itwill be understood by those of skill in the art which lymphomas aretypically characterized as “intermediate-” and “high-grade.” Forinstance, “mantle cell lymphoma” as defined in the REAL classificationsystem may appear as both indolent and more aggressive forms, anddepending on the severity may be classified as an intermediate- orhigh-grade lymphoma.

For instance, the U.S. National Cancer Institute (NCI) has in turndivided some of the REAL classes into more clinically useful “indolent”or “aggressive” lymphoma designations. “Aggressive” lymphomas includediffuse mixed and large cell lymphoma, Burkitt's lymphoma/diffuse smallnon-cleaved cell lymphoma, Lymphoblastic lymphoma, Mantle cell lymphomaand AIDS-related lymphoma. These lymphomas would therefor be consideredat least “intermediate” or “high-grade,” and would therefor benefit fromthe therapeutic methods of the present invention.

While strict classifications of some lymphomas may be difficult, thelymphomas treatable by the present invention are generally characterizedby a high number of circulating B cells, possible bone marrowinvolvement, bulky disease, or the involvement of extralymphatic organor sites.

Often, the patients which will most benefit from the disclosedtherapeutic methods are those patients who are refractory to other typesof treatments, or who have relapsed following other types of treatments,such as chemotherapy or radiotherapy. However, the monoclonal antibodytreatments disclosed in the present invention will be beneficial also tonewly diagnosed patients, and may have a synergistic effect indecreasing the chance of relapse if administered in conjunction withother conventional therapies.

For instance, the methods of the present invention include methodscomprising the administration of both monoclonal antibodies (orfragments thereof) to CD20 along with a chemotherapeutic regimen.Depending on the particular patient, said chemotherapy may beadministered simultaneously or sequentially in either order.“Simultaneously” means either concurrently or during the same timeperiod such that the circulating half-lives of the therapeutic agentsoverlaps.

Chemotherapeutic regimens which may be combined with the antibodytreatments of the present invention include CHOP, ICE, Mitozantrone,Cytarabine, DVP, ATRA, Idarubicin, hoelzer chemotherapy regime, La Lachemotherapy regime, ABVD, CEOP, 2-CdA, FLAG & IDA with or withoutsubsequent G-CSF treatment), VAD, M & P, C-Weekly, ABCM, MOPP and DHAP.The most preferred chemotherapeutic regimen is CHOP.

The primary anti-CD20 antibodies of the present invention are preferablyhuman antibodies, or chimeric or humanized antibodies which areengineered with human constant region domains, such that the antibodiesare able to stimulate human effector functions. A preferred antibody tobe used in the methods of the present invention is RITUXAN® rituximab(IDEC Pharmaceuticals, Inc.).

Rituximab is one of a new generation of monoclonal antibodies developedto overcome limitations encountered with murine antibodies, includingshort half-life, limited ability to stimulate human effector functions,and immunogenicity. Rituximab is a genetically engineered monoclonalantibody with murine light-and heavy-chain variable regions and humangamma I heavy-chain and kappa light-chain constant regions. The chimericantibody is composed of two heavy chains of 451 amino acids and twolight chains of 213 amino acids and has an approximate molecular weightof 145 kD.

Rituximab is more effective than its murine parent in fixing complementand mediating ADCC, and it mediates CDC in the presence of humancomplement. The antibody inhibits cell growth in the B-cell lines FL-18,Ramos, and Raji, sensitizes chemoresistant human lymphoma cell lines todiphtheria toxin, ricin, CDDP, doxorubicin, and etoposide, and inducesapoptosis in the DHL-4 human B-cell lymphoma line in a dose-dependentmanner. In humans, the half-life of the antibody is approximately 60hours after the first infusion and increases with each dose to 174 hoursafter the fourth infusion. The immunogenicity of the antibody is low; of355 patients in seven clinical studies, only three (<1%) had adetectable anti-chimeric antibody (HACA) response.

The methods of the present invention may comprise administration of aradiolabeled antibody which binds to a protein on the surface ofcancerous B cells. Such radiolabeled antibodies are preferablyadministered following administration of the human, chimeric orhumanized antibody, which will decrease the amount of cancerous B cellsin the bone marrow and lessen the likelihood of unwanted myeloablativesuppression due to antibody binding to tumor cells in the marrow.Moreover, while CD20 is an ideal target for the immunotherapy of thepresent invention, it is possible that radiolabeled antibodies directedto other B cell surface antigens may also be used in the methods of thepresent invention. In particularly preferred embodiments, theradiolabeled antibodies are used in conjunction with unlabeledantibodies.

Approximately 80% of non-Hodgkin's lymphomas are B-cell-malignanciesand >95% of these express the CD20 antigen on the cell surface. Thisantigen is an attractive target for immunotherapy because it is foundexclusively on B cells, and not on hematopoietic stem cells, pro-Bcells, normal plasma cells, or other normal tissues. It is not shed fromthe cell surface and does not modulate upon antibody binding.

The radiolabeled antibodies of the present invention may be labeled withany alpha or beta emitting radioisotope. However, a preferred isotope is⁹⁰Y, and a preferred antibody is Y2B8. Y2B8 was engineered from the samemurine antibody, 2B8, as was rituximab. The 2B8 antibody has also beenconjugated to different radiolabels for diagnostic and therapeuticpurposes. To this end, copending application Ser. Nos. 08/475,813,08/475,815 and 08/478,967, herein incorporated by reference in theirentirety, disclose radiolabeled anti-CD20 conjugates for diagnostic“imaging” of B cell lymphoma tumors before administration of therapeuticantibody. For instance, the “In2B8” conjugate comprises the murinemonoclonal antibody, 2B8, attached to Indium[111] (¹¹¹In) via abifunctional chelator, i.e., MX-DTPA (diethylenetriaminepentaaceticacid), which comprises a 1:1 mixture of1-isothiocyanatobenzyl-3-methyl-DTPA and1-methyl-3-isothiocyanatobenzyl-DTPA. Indium-[111] is selected as adiagnostic radionuclide because it emits gamma radiation and finds priorusage as an imaging agent.

Patents relating to chelators and chelator conjugates are known in theart. For instance, U.S. Pat. No. 4,831,175 of Gansow is directed topolysubstituted diethylenetriaminepentaacetic acid chelates and proteinconjugates containing the same, and methods for their preparation. U.S.Pat. Nos. 5,099,069, 5,246,692, 5,286,850, and 5,124,471 of Gansow alsorelate to polysubstituted DTPA chelates. These patents are incorporatedherein in their entirety.

The specific bifunctional chelator used to facilitate chelation inapplication Ser. Nos. 08/475,813, 08/475,815 and 08/478,967 was selectedas it possesses high affinity for trivalent metals, and provides forincreased tumor-to-non-tumor ratios, decreased bone uptake, and greaterin vivo retention of radionuclide at target sites, i.e., B-cell lymphomatumor sites. However, other bifunctional chelators are known in the artand may also be beneficial in tumor therapy.

Also disclosed in application Ser. Nos. 08/475,813, 08/475,815 and08/478,967 are radiolabeled therapeutic antibodies for the targeting anddestruction of B cell lymphomas and tumor cells. In particular, the Y2B8conjugate comprises the same anti-human CD20 murine monoclonal antibody,2B8, attached to yttrium-[90] (⁹⁰Y) via the same bifunctional chelator.This radionuclide was selected for therapy for several reasons. The 64hour half-life of ⁹⁰Y is long enough to allow antibody accumulation bythe tumor and, unlike e.g. ¹³¹I, it is a pure beta emitter of highenergy with no accompanying gamma irradiation in its decay, with a rangeof 100 to 1000 cell diameters. The minimal amount of penetratingradiation allows for outpatient administration of ⁹⁰Y-labeledantibodies. Furthermore, internalization of labeled antibodies is notrequired for cell killing, and the local emission of ionizing radiationshould be lethal for adjacent tumor cells lacking the target antigen.

Because the ⁹⁰Y radionuclide was attached to the 2B8 antibody using thesame bifunctional chelator molecule MX-DTPA, the Y288 conjugatepossesses the same advantages discussed above, e.g., increased retentionof radionuclide at a target site (tumor). However, unlike ¹¹¹In, itcannot be used for imaging purposes due to the lack of gamma radiationassociated therewith. Thus, a diagnostic “imaging” radionuclide, such as¹¹¹In, can be used for determining the location and relative size of atumor prior to and/or following administration of therapeutic chimericor ⁹⁰Y-labeled antibodies in the combined regimens of the invention.Additionally, indium-labeled antibody enables dosimetric assessment tobe made.

Depending on the intended use of the antibody, i.e., as a diagnostic ortherapeutic reagent, other radiolabels are known in the art and havebeen used for similar purposes . For instance, radionuclides which havebeen used in clinical diagnosis include ¹³¹I, ¹²⁵I, ¹²³I, ⁹⁹Tc, ⁶⁷Ga, aswell as ¹¹¹In. Antibodies have also been labeled with a variety ofradionuclides for potential use in targeted immunotherapy (Peirersz etal., 1987). The use of monoclonal antibody conjugates for the diagnosisand treatment of cancer. Immunol. Cell Biol. 65: 111-125). Theseradionuclides include ¹⁸⁸Re and ¹⁸⁶Re as well as ⁹⁰Y, and to a lesserextent ¹⁹⁹Au and ⁶⁷Cu. U.S. Pat. No. 5,460,785 provides a listing ofsuch radioisotopes and is herein incorporated by reference.

As reported in copending application Ser. Nos. 08/475,813, 08/475,815and 08/478,967 administration of the radiolabeled Y2B8 conjugate, aswell as unlabeled chimeric anti-CD20 antibody (rituximab), resulted insignificant tumor reduction in mice harboring a B cell lymphoblastictumor. Moreover, human clinical trials reported therein showedsignificant B cell depletion in low-grade NHL lymphoma patients infusedwith rituximab. In fact, rituximab has recently been heralded thenation's first FDA-approved anti-cancer monoclonal antibody. Inaddition, U.S. application Ser. No. 08/475,813, herein incorporated byreference, discloses sequential administration of RITUXAN® (rituximab),a chimeric anti-CD20, with both or either indium-labeled oryttrium-labeled murine monoclonal antibody for the treatment oflow-grade NHL. Although the radiolabeled antibodies used in thesecombined therapies are murine antibodies, initial treatment withchimeric anti-CD20 sufficiently depletes the B cell population such thatthe HAMA response is decreased, thereby facilitating a combinedtherapeutic and diagnostic regimen. Moreover, it was shown in U.S.application Ser. No. 08/475,813 that a therapeutically effective dosageof the yttrium-labeled anti-CD20 antibody following administration ofrituximab is sufficient to (a) clear any remaining peripheral blood Bcells not cleared by the chimeric anti-CD20 antibody; (b) begin B celldepletion from lymph nodes; or (c) begin B cell depletion from othertissues.

Autologous bone marrow transplantation is often a successfulaccompaniment to myeloablative therapy in helping to restore the immunesystem to patients who have undergone radiotherapy or chemotherapy.However, as discussed above, the patients who will benefit by themethods disclosed herein will often have lymphoma accompanied by bonemarrow involvement. For such patients, there are often too manycancerous cells in the marrow to perform autologous transplantation.

When there is bone marrow involvement accompanying the intermediate- orhigh-grade lymphoma, such patients may benefit by prior treatment withhuman, chimeric or humanized anti-CD20 antibody before bone marrowharvesting in order to decrease the quantity of tumor cells in the bonemarrow or stem cell preparation. In fact, rituximab can be administeredat induction, in vivo purging, mobilization, conditioning,post-transplant reinfusion and at any other time during bone marrow orstem cell transplant for the purpose of improving the survival rate oftransplant recipients. “Induction” is meant to refer to the initialtherapies aimed at achieving induction of remission. Typically,induction involves the administration of some type of chemotherapy,i.e., CHOP.

The phrase “in vivo purging” is meant to refer to treatment particularlygeared toward purging tumor cells from the bone marrow within thepatient, although certainly such treatment might be beneficial for tumorcells in the peripheral blood and at other sites as well. Such a stepmay precede the harvest of bone marrow as a means of decreasing thenumber of tumor cells therein. Rituximab and other chimeric lymphomacell-depleting antibodies provide an advantage in this regard overradiolabeled antibodies in that they may be used to purge the bonemarrow of cancerous cells without damaging healthy progenitors.

“Mobilization” refers to the process by which stem cells are mobilizedto leave the bone marrow and enter the circulatory system, and providesan alternative to bone marrow harvest per se as a source of stem cellsfor transplantation. Mobilization is typically achieved by administeringa short burst of chemotherapy and/or growth factors. The growth factorG-CSF is commonly used, but others may be used according to theknowledge of the skilled artisan.

Typically, during mobilization, stem cells are separated from blood(which is then put back into the patient), and the stem cells are frozenuntil the patient is ready to be reinfused. Ex vivo purging withrituximab, or other antibodies known in the art to be useful for thispurpose, may then be used to deplete tumor cells in the stem cellpreparation.

“Conditioning” refers to a process by which the patient is prepared toreceive the autologous bone marrow reinfusion or allogeneic transplant.This is typically accomplished with a very high dose of chemotherapy inorder to deplete all bone marrow cells, i.e., both healthy cells andtumor cells, from the bone marrow. Chemotherapeutic drugs that may begiven at sufficiently high doses without risking the patient's life,e.g. cyclophosphamide, are known in the art.

Thus, with rituximab treatment at the various stages of transplantation,marrow may be harvested prior to myeloablative radiotherapy, andreintroduced subsequent to such therapy with less concern aboutreintroducing tumor cells originally harvested with the marrow back intothe patient. Of course, the patient may then benefit by additional orsubsequent treatment with chimeric anti-CD20 antibody as part of amaintenance regimen, or by administration of a radiolabeled antibodysuch as Y2B8 to further decrease the chance of relapse.

The methods of the present invention also encompass combined therapycomprising administration of at least one cytokine along with ananti-CD20 antibody or fragment thereof. Such a cytokine may beadministered simultaneously or sequentially in any order. In particular,cytokines may be useful in upregulating the expression of CD20 on thesurface of cancerous B cells prior to administration of the anti-CD20antibody. Cytokines useful for this purpose include IL-4, GM-CSF andTNF-alpha, and possibly others.

Cytokines may also be administered simultaneously or within the sametime frame in order to increase or control certain effector functionsmediated by the therapeutic antibody. Cytokines useful for this purposeinclude interferon alpha, G-CSF and GM-CSF, and possibly others.

Preferred dosage regimens and exemplary embodiments will now beillustrated by way of the following data.

Single-Agent Studies

In a study conducted in Europe and Australia, alternative dosingschedules were evaluated in 54 relapsed or refractory intermediate- orhigh-grade NHL patients (Coiffier B, Haioun C, Ketterer N, Engert A,Tilly H, Ma D, Johnson P, Lister A, Feuring-Buske M, Radford J A,Capdeville R, Diehl V, Reyes F. Rituximab (anti-CD20 monoclonalantibody) for the treatment of patients with relapsing or refractoryaggressive lymphoma: a multicenter phase H study. Blood 1998;92:1927-1932).

Rituximab was infused at 375 mg/m2 weekly for 8 doses or at 375 mg/m2once followed by 500 mg/m2 weekly for 7 doses. The ORR was 31%; (CR 9%,PR 22%) no significant difference between the dosing regimens wasobserved. Patients with diffuse large-cell lymphoma (N=30) had an ORR of37% and those with mantle-cell lymphoma (N=12) had an ORR of 33%.

Treatment of Bulky Disease

Contrary to early assumptions about antibody therapy being useful onlyin micrometastatic disease, rituximab is quite active in high bulkdisease. In a separate study, 31 patients with relapsed or refractory,bulky low-grade NHL (single lesion of >10 cm in diameter) received 375mg/m² rituximab as four weekly infusions. Twelve of 28 evaluablepatients (43%) demonstrated a CR (1, 4%) or PR (11, 39%) (Davis T, WhiteC, Grillo-López A, Velasquez W, Link B, Maloney D, Dillman R, WilliamsM, Mohrbacher A, Weaver R, Dowden S, Levy R. Rituximab: First report ofa Phase II (PII) trial in NHL patients (pts) with bulky disease. Blood1998; 92 (10 Suppl 1):414a).

This suggests that with the appropriate dosages depending on the extentof disease and the number of circulating tumor cells (i.e., such as theincreased dosages described above), rituximab therapy will also beuseful for more aggressive intermediate- or high-grade NHLs accompaniedby bulky disease.

Combination of Rituximab and CHOP Chemotherapy

In another study, 31 patients with intermediate- or high-grade NHL (19females, 12 males, median age 49) received rituximab on Day 1 of each ofsix 21-day cycles of CHOP: Link B, Grossbard M, Fisher R, Czuczman M,Gilman P, Lowe A, Vose J. Phase II pilot study of the safety andefficacy of rituximab in combination with CHOP chemotherapy in patientswith previously untreated- or high-grade NHL. Proceedings of theAmerican Society of Clinical Oncology 1998; 17:3a). Of 30 evaluablepatients, there were 19 CR (63%) and 10 PR (33%), for an ORR of 96%.This regimen was considered well tolerated and may result in higherresponse rates than with rituximab or CHOP alone. The NCI Division ofCancer Treatment and Diagnosis is collaborating with IDEC

Pharmaceuticals Corporation to explore rituximab treatment in otherindications. A Phase II trial of CHOP versus CHOP and rituximab is beingconducted by ECOG, CALGB, and SWOG in older patients (>60 years) withmixed, diffuse large cell, and immunoblastic large cell histology NHL(N=630 planned). This study includes a secondary randomization tomaintenance with rituximab versus nonmaintenance.

A Phase III trial of rituximab and CHOP in 40 patients with previouslyuntreated mantle-cell lymphoma is also ongoing at the Dana FarberInstitute. Rituximab is administered on Day 1 and CHOP is given on Days1-3 every 21 days for 6 cycles. Accrual for this study has beencompleted. A Phase II trial of CHOP followed by rituximab in newlydiagnosed follicular lymphoma conducted by SWOG has also been completed.Results of these two trials are being analyzed.

A Phase II trial of CHOP and rituximab versus CHOP alone in HIV-relatedNHL conducted by the AIDS Malignancy Consortium is ongoing; 120 patientsare planned.

Rituximab after Myeloablative Therapy Relapse

Rituximab has shown promising early results in patients with relapsedintermediate-grade NHL after high-dose therapy with autologous PBSCsupport. Six of seven patients responded (1 CR and 5 PR) and one patienthad stable disease; therapy was well tolerated (Tsai, D, Moore H, PorterD, Vaughn D, Luger S, Loh R, Schuster S, Stadtmauer E. Progressiveintermediate grade non-Hodgkin's lymphoma after high dose therapy andautologous peripheral stem cell transplantation (PSCT) has a highresponse rate to rituximab. Blood 1998; 92:415a, #1713).

The invention claimed is:
 1. A method of treating a patient with diffuse large cell lymphoma comprising administering anti-CD20 antibody and chemotherapy to the patient, wherein the patient is >60 years old, wherein the chemotherapy comprises CHOP (cyclophosphamide, hydroxydaunorubicin/doxorubicin, vincristine, and prednisone/prednisolone), and wherein the anti-CD20 antibody is administered to the patient in combination with stem cell transplantation regimen.
 2. The method of claim 1, wherein the antibody comprises a chimeric anti-CD20 antibody.
 3. The method of claim 2, wherein the antibody comprises rituximab.
 4. The method of claim 1, wherein the lymphoma is accompanied by bone marrow involvement.
 5. A method of treating a patient with diffuse large cell lymphoma comprising administering rituximab and CHOP (cyclophosphamide, hydroxydaunorubicin/doxorubicin, vincristine, and prednisone/prednisolone) to the patient, in combination with stem cell transplantation, wherein the patient is >60 years old. 